Composition and method for providing a patterned metal layer having high conductivity

ABSTRACT

Disclosed is a method for making a metal pattern with high conductivity comprising providing a patterned substrate comprising a patterned catalyst layer on a base substrate by a thermal imaging method followed by plating to provide the metal pattern. The metal patterns provided are suitable for electrical devices including electromagnetic interference shielding devices and touchpad sensors.

FIELD OF INVENTION

The invention relates to methods for providing conducting metal patternsfor electrical applications.

BACKGROUND

Electromagnetic interference shields and touch screens for lighttransmissive surfaces, such as displays, typically include a conductingmetal mesh mounted on a substrate. The mesh allows a substantial portionof visible light to pass, while shielding other electromagneticradiation. There are a variety of methods available to manufacture suchmetal mesh articles. For instance, U.S. Pat. No. 6,717,048 discloses anelectromagnetic shielding plate having a glass substrate and a geometricpattern formed on the substrate in an off-set printing process.

New methods useful for providing conducting metal patterns are neededthat allow high resolution and precise digital control of the patternbeing formed; for instance with a capability to prepare mesh having finelines, down to 10 micron line-width. In addition, it is desirable tominimize wet processing steps and the use of solvents, etchants, andmasks, typically used in conventional photolithography methods.Eliminating wet processing steps and solvents would give an overallmethod that is significantly more environmental friendly thanconventional methods used in making metal mesh.

SUMMARY OF INVENTION

One embodiment is a method for making a patterned metal layer havinghigh conductivity comprising:

providing a patterned substrate comprising a patterned catalyst layer ona base substrate; said patterned substrate made by a thermal imagingmethod comprising:

-   -   (a) providing a thermal transfer donor comprising a base film        and a catalyst transfer layer, wherein the catalyst transfer        layer comprises: (i) a catalyst fraction; optionally (ii) an        adhesion promoter fraction; and, optionally and        independently, (iii) a polymer binder fraction;    -   (b) contacting the thermal transfer donor with a receiver,        wherein the receiver comprises a base layer; and    -   (c) transferring at least a portion of the catalyst transfer        layer onto the receiver by        thermal transfer to provide a patterned receiver as said        patterned substrate; and

plating metal onto said patterned substrate, to provide the patternedmetal layer in connectivity with the patterned catalyst layer.

Another embodiment is a thermal transfer donor comprising a base film, acatalyst transfer layer (A), and a LTHC layer interposed between saidbase film and said catalyst transfer layer (A), said catalyst transferlayer (A) comprising:

-   -   (i) about 1.0 to about 99 wt % of a catalyst fraction (A), based        on the total weight of the catalyst layer, said catalyst        fraction comprising metal particles selected from Ag, Cu, and        alloys thereof;    -   (ii) about 0.5 to about 10 wt % of an adhesion promotor fraction        selected from glass frit; and metal hydroxides and alkoxides;        and    -   (iii) about 0.5 to about 98.5 wt % of a polymer binder.

Another embodiment is a thermal transfer donor comprising, in layeredsequence, a base film, a catalyst transfer layer (B) and an adhesionpromoter layer, said catalyst transfer layer (B) comprising:

-   -   (i) about 1.0 to about 99 wt % of a catalyst fraction, based on        the total weight of the catalyst layer, said catalyst fraction        comprising metal particles selected from Ag, Cu, and alloys        thereof;    -   (iii) about 1.0 to about 99 wt % of a polymer binder; and        wherein the adhesion promoter layer comprises material selected        from glass frit; and metal hydroxides and alkoxides.

Another embodiment is an electronic device having a patterned metallayer on a substrate, said substrate substantially transparent tovisible light; said patterned metal layer comprising, in layeredsequence on said substrate: an adhesion promoter layer, a catalystlayer, and a plated metal layer; and said patterned metal layer havingat least one line of width of about 1 millimeter or less.

BRIEF DESCRIPTION OF FIGURES

FIGS. 1A and B are cross-sectional views of various thermal imagingdonors 100 in accordance with embodiments of the invention.

FIG. 2A is a cross-sectional view of thermal imaging receiver 200 havinga receiver base layer 202.

FIG. 2B is a cross-sectional view of a receiver 200 having a patternedblack layer 204.

FIG. 3 illustrates the laser-mediated transfer process for preparingpatterned substrates.

FIGS. 4A and B illustrate separation of spent thermal transfer donor andreceiver elements after thermal transfer of the patterned catalystlayer.

FIG. 5 is a side-view of a patterned metal layer provided one embodimentof the invention.

FIG. 6 is a photomicrograph of a patterned metal layer.

FIG. 7 shows a photomicrograph of a plated pattern within the bounds ofa patterned black layer provided by the method of the invention.

DETAILED DESCRIPTION

All trademarks herein are designated with capital letters.

Herein the terms “acrylic”, “acrylic resin”, “(meth)acrylic resins”, and“acrylic polymers”, are synonymous unless specifically definedotherwise. These terms refer to the general class of addition polymersderived from the conventional polymerization of ethylenicallyunsaturated monomers derived from methacrylic and acrylic acids andalkyl and substituted-alkyl esters thereof. The terms encompasshomopolymers and copolymers. The terms encompass specifically thehomopolymers and copolymers of methyl (meth)acrylate, ethyl(meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate,(meth)acrylic acid and glycidyl (meth)acrylate. The term copolymerherein encompasses polymers derived from polymerization of two or moremonomers, unless specifically defined otherwise. The term (meth)acrylicacid encompasses both methacrylic acid and acrylic acid. The term(meth)acrylate, encompasses methacrylate and acrylate.

The terms “styrene acrylic polymers”, “acrylic styrene” and “styreneacrylic” are synonymous and encompass copolymers of the above described“acrylic resins” with styrene and substituted styrene monomers, forinstance alpha-methyl styrene.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

Also, use of “a” or “an” are employed to describe elements andcomponents described herein. This is done merely for convenience and togive a general sense of the scope of the invention. This descriptionshould be read to include one or at least one and the singular alsoincludes the plural unless it is obvious that it is meant otherwise.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of embodiments of the present invention, suitablemethods and materials are described below. In case of conflict, thepresent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and notintended to be limiting.

To the extent not described herein, many details regarding specificmaterials, processing acts, and circuits are conventional and may befound in textbooks and other sources within the organic light-emittingdiode display, photodetector, photovoltaic, and semiconductive memberarts.

The term “mesh” herein refers to a weblike pattern or construction. Amesh includes, for instance, a free-standing screen, and a weblikepattern adhered or mounted on a base layer.

The terms “thermal imaging donor” and “thermal transfer donor” may beused interchangeably herein, and are intended to be synonymous.

One embodiment of the invention is a method for making a patterned metallayer having high conductivity. The method requires providing apatterned substrate comprising a patterned catalyst layer on a basesubstrate. The embodiment requires the patterned substrate be made by athermal imaging method comprising:

(a) providing a thermal transfer donor comprising a base film and acatalyst transfer layer, wherein the catalyst layer comprises: (i) acatalyst fraction; optionally (ii) an adhesion promoter fraction; and,optionally and independently, (iii) a polymer binder fraction.

(b) contacting the donor with a receiver, wherein the receiver comprisesa base layer; and

(c) transferring at least a portion of the catalyst layer onto thereceiver by thermal transfer to provide a patterned receiver as saidpatterned substrate; followed by plating of metal onto said patternedsubstrate, to provide the patterned metal layer in connectivity with thepatterned catalyst layer. The patterned metal layer provided by themethod can be in the form of a metal mesh adhered to the substrate or,if so desired, detached from the substrate.

Herein first will be disclosed the details of the thermal transfer donorrequired for the thermal imaging method; followed by the details of thethermal imagining method; and the plating step; to provide a patternedmetal layer having high conductivity.

Thermal Transfer Donor

One embodiment of the invention is a multilayer thermal transfer donor.In various embodiments the thermal transfer donor comprises, in layeredsequence, a base film, and optional LTHC layer, a catalyst transferlayer and an optional protective strippable cover layer. Otherembodiments can include one or more additional layers interposed betweenthe base film and the catalyst transfer layer and/or on top of the metaltransfer layer. Thus, one or more other conventional thermal transferdonor element layers can be included in the thermal imaging donor,including but not limited to an interlayer, primer layer, release layer,ejection layer, thermal insulating layer, underlayer, adhesive layer,humectant layer, and light attenuating layer.

FIG. 1A is a cross-sectional view of a thermal imaging donor 100 inaccordance with one embodiment of the invention. Thermal imaging donor100 comprises base film 102, and a catalyst layer 106 on the surface ofthe base film 102. Base film 102 provides support to the other layers ofthermal imaging donor 100. Base film 102 comprises a flexible polymerfilm that is preferably transparent. A suitable thickness for base film102 is about 25 μm to about 200 μm, although thicker or thinner supportlayers may be used. The base film may be stretched by standard processesknown in the art for producing oriented films and one or more otherlayers, such as a light-to-heat-conversion (LTHC) layer, may be coatedonto the base film prior to completion of the stretching process.Preferred base films comprise a material selected from the groupconsisting of: polyethylene terephthalate (PET), polyethylenenaphthalate (PEN), triacetyl cellulose and polyimide.

A light-attenuating agent (absorber or diffuser) may be present in adiscrete layer or incorporated in one of the other functional layers ofthe thermal transfer donor, such as the base film, the LTHC layer or thecatalyst layer. In one embodiment, the base film comprises a smallamount (typically 0.2% to 0.5% by weight of the base film) of alight-attenuating agent such as a dye, which can assist in the focusingof the radiation source onto the radiation-absorber in the LTHC layerduring the thermal imaging step, thereby improving the efficiency of theheat transfer. U.S. Pat. No. 6,645,681 describes this and other ways inwhich the base film may be modified to assist in the focusing of a laserradiation source in which the equipment comprises an imaging laser and anon-imaging laser, and wherein the non-imaging laser has a lightdetector that is in communication with the imaging laser. The wavelengthranges at which the imaging and non-imaging laser operate (typically inthe range from about 350 nm to about 1500 nm) determine the wavelengthranges in which the absorber(s) and/or diffuser(s) are active andinactive. For example, if the non-imaging laser operates in about the670 nm region and the imaging laser at 830 nm, it is preferred that theabsorber and/or diffuser operate to absorb or diffuse light in the 670nm region, rather than in the 830 nm region. Herein, the lightattenuating agent preferably absorbs or diffuses light in the visibleregion, and in one embodiment absorbs around 670 nm. Suitablelight-attenuating agents are well known in the art and include thecommercially available Disperse Blue 60 and Solvent Green 28 dyes andcarbon black. Preferably the amount of light-attenuating agent issufficient to achieve an optical density (OD) of 0.1 or greater at somewavelength of about 400 to about 750 nm, more preferably about 0.3 toabout 1.5.

Light-to-Heat Conversion Layer (LTHC)

The thermal imaging donor may, optionally, have alight-to-heat-conversion layer (LTHC), interposed between the base filmand the other layers as illustrated in FIG. 1B. Thermal imaging donor100 comprises a LTHC layer 108 interposed between base film 102 and thecatalyst layer 106. LTHC layer 108 is incorporated as a part of thermalimaging donor 100 for radiation-induced thermal transfer to couple theenergy of light radiated from a light-emitting source into the thermaltransfer donor. Typically, the radiation absorber in the LTHC layer (orother layers) absorbs light in the infrared, visible, and/or ultravioletregions of the electromagnetic spectrum and converts the absorbed lightinto heat. The radiation absorber is typically highly absorptive,providing an OD at the wavelength of the imaging radiation of 0.1 to 3or higher and preferably 0.2 to 2. Suitable radiation absorbingmaterials can include, for example, dyes (e.g., visible dyes,ultraviolet dyes, infrared dyes, fluorescent dyes, andradiation-polarizing dyes), pigments, metals, metal compounds,metallized films, and other suitable absorbing materials.

Suitable radiation absorbers and binders for LTHC layers are well-knownin the art, and lists and references can be found, for example, inPCT/US05/38010; PCT/US05/38009; U.S. Pat. No. 6,228,555 B1; Matsuoka,M., “Infrared Absorbing Materials”, Plenum Press, New York, 1990; andMatsuoka, M., Absorption Spectra of Dyes for Diode Lasers, BunshinPublishing Co., Tokyo, 1990.

Preferred classes of near-infrared dyes for LTHC layers are cyaninecompounds selected from the group consisting of: indocyanines,phthalocyanines including polysubstituted phthalocyanines andmetal-containing phthalocyanines, and merocyanines. Sources of suitableinfrared-absorbing dyes include H. W. Sands Corporation (Jupiter, Fla.,US), American Cyanamid Co. (Wayne, N.J.), Cytec Industries (WestPaterson, N.J.), Glendale Protective Technologies, Inc. (Lakeland, Fla.)and Hampford Research Inc. (Stratford, Conn.). Preferred dyes for LTHC,carrier layers and transfer layers are 3H-indolium,2-[2-[2-chloro-3-[(1,3-dihydro-1,3,3-trimethyl-2H-indol-2-ylidene)ethylidene]-1-cyclopenten-1-yl]ethenyl]-1,3,3-trimethyl-,salt with trifluoromethanesulfonic acid (1:1) having CAS No.[128433-68-1] and molecular weight of about 619 grams per mole,available from Hampford Research Inc, Stratford, Conn., as TIC-5c;2-(2-(2-chloro-3-(2-(1,3-dihydro-1,1-dimethyl-3-(4-sulphobutyl)-2H-benz[e]indol-2-ylidene)ethylidene)-1-cyclohexene-1-yl)ethenyl)-1,1-dimethyl-3-(4-sulphobutyl)-1H-benz[e]indolium,inner salt, free acid having CAS No. [162411-28-1], available from H. W.Sands Corp, as SDA 4927; and indolenine dyes SDA 2860 and SDA 4733 fromH. W. Sands Corp. SDA 4927 is an especially preferred dye for the LTHClayer.

An LTHC layer may include a particulate radiation absorber in a binder.Examples of suitable pigments include carbon black and graphite.

The weight percent of the radiation absorber in the layer, excluding thesolvent in the calculation of weight percent, is generally from 1 wt %to 85 wt %, preferably from 3 wt % to 60 wt %, and most preferably from5 wt % to 40 wt %, depending on the particular radiation absorber(s) andbinder(s) used in the LTHC layer.

Suitable binders for use in the LTHC layer include film-formingpolymers, such as, for example, phenolic resins (e.g., novolak andresole resins), polyvinyl butyral resins, polyvinyl acetates, polyvinylacetals, polyvinylidene chlorides, polyacrylates, and styrene acrylics.The % transmittance of the LTHC layer is affected by the identity andamount of the radiation-absorber and the thickness of the LTHC layer.The LTHC layer preferably exhibits radiation transmission of about 20%to about 80%, more preferably of about 40% to about 50%, at thewavelength of the imaging radiation used in the thermal transfer imagingprocess. When a binder is present, the weight ratio of radiationabsorber to binder is generally from about 5:1 to about 1:1000 byweight, preferably about 2:1 to about 1:100 by weight. A polymeric ororganic LTHC layer is coated to a thickness of 0.05 μm to 20 μm,preferably, 0.05 μm to 10 μm, and, more preferably, 0.10 μm to 5 μm.

In preferred embodiments of this invention, the LTHC layer may include abroad variety of water-soluble or water-dispersible polymeric binderswith compositions as disclosed in the above referenced PCT/US05/38010and PCT/US05/38009. Preferably, the average particle size of awater-dispersible binder in its aqueous phase is less than 0.1 micron,and more preferably less than 0.05 micron, and preferably having anarrow particle size distribution. Preferred water-soluble orwater-dispersible polymeric binders for LTHC layers useful in theinvention are those selected from the group: acrylic resins andhydrophilic polyesters and more preferably from sulphonated polyestersas described in the above referenced PCT/US05/38009.

Other preferred polymeric binders for LTHC layers are maleic anhydridepolymers and copolymers including those comprising functionalityprovided by treating the maleic anhydride polymers and/or copolymerswith alcohols, amines, and alkali metal hydroxides. Specific families ofmaleic anhydride based copolymers comprise the structure represented byformula (III)

wherein x and z are any positive integer;wherein y is zero or any positive integer;R₂₁ and R₂₂ can be the same or different, and individually are hydrogen,alkyl, aryl, aralkyl, cycloalkyl, and halogen, provided that one of R₂₁and R₂₂ is an aromatic group;R₃₁, R₃₂, R₄₁ and R₄₂ are the same or different groups, which can behydrogen or alkyl of one to about five carbon atoms; andR₅₀ is functional group selected from:

a) alkyl, aralkyl, alkyl-substituted aralkyl radicals containing fromone to about twenty carbon atoms;

b) oxyalkylated derivatives of alkyl, aralkyl, alkyl-substituted aralkylradicals containing from about two to about four carbon atoms in eachoxyalkylene group, which can be of one to about twenty repeating units;

c) oxyalkylated derivatives of alkyl, aralkyl, alkyl-substituted aralkylradicals containing from about two to about four carbon atoms in eachoxyalkylene group, which can be of one to about six repeating units;

d) at least one unsaturated moiety;

e) at least one heteroatom moiety;

f) alkaline molecules capable of forming salts selected from Li, Na, Kand NH₄ ⁺; and

g) combinations thereof.

A preferred maleic anhydride polymer for LTHC layers comprises acopolymer of formula (III), wherein R₂₁, R₃₁, R₃₂, R₃₃, R₄₁, R₄₂, R₄₃,are individually hydrogen, R₂₂ is phenyl, and R₅₀ is 2-(n-butoxy)ethyl.A specific example of a maleic anhydride copolymer useful in LTHC layersis a styrene maleic anhydride copolymer such as SMA 1440H, a product ofSartomer Corporation, Exton, Pa.

In one embodiment of the invention, a preferred LTHC layer comprises oneor more water-soluble or water-dispersible radiation-absorbing cyaninecompound(s) selected from the group consisting of: indocyanines,phthalocyanines including polysubstituted phthalocyanines andmetal-containing phthalocyanines, and merocyanines; and one or morewater-soluble or water-dispersible polymeric binders selected from thegroup consisting of: acrylic resins, hydrophilic polyesters, sulphonatedpolyesters, and maleic anhydride homopolymers and copolymers. A mostpreferred LTHC layer further comprises one or more release modifiersselected from the group consisting of: quaternary ammonium cationiccompounds; phosphate anionic compounds; phosphonate anionic compounds;compounds comprising from one to five ester groups and from two to tenhydroxyl groups; alkoxylated amine compounds; and combinations thereof.

Metal radiation absorbers also may be used as LTHC layers, either in theform of particles or as films deposited by various techniques such asthermal evaporation, e-beam heating and sputtering, as disclosed in U.S.Pat. No. 5,256,506. Nickel and chromium are preferred metals for theLTHC layer 108 with chromium being especially preferred. Any othersuitable metal for the heating layer can be used. The preferredthickness of the metal heating layer depends on the optical absorptionof the metals used. For chromium, nickel/vanadium alloy or nickel, alayer of 80-100 Angstroms is preferred.

Preferred radiation absorbers for LTHC layers utilized herein areselected from the group consisting of: metal films selected from Cr andNi; carbon black; graphite; and especially preferred are near infrareddyes with an absorption maxima in the range of about 600 to 1200 nmwithin the LTHC layer.

Catalyst Transfer Layer

The catalyst transfer layer and the patterned catalyst layer provided bythermal transfer comprises: (i) a catalyst fraction; optionally (ii) anadhesion promoter fraction; and, optionally and independently, (iii) apolymer binder fraction. The catalyst transfer layer can be anon-conducting layer or a conducting layer. The catalyst transfer layerthickness can be anywhere from about 5 nm to about 5 μm, and morepreferably, about 100 nm to about 3 μm.

The catalyst fraction can be a conductive material, or a non-conductivematerial, depending upon the requisite properties of the patternedcatalyst layer, treating conditions, method of plating, etc. Thecatalyst fraction comprises one or more catalyst(s) that, when appliedto a substrate, can provide plating, or metal deposition, when subjectedto electrolytic plating or electroless plating conditions.

Common catalysts for electroless plating are discussed in “ElectrolessNickel Plating” Wolfgang Riedel, Finishing Publications Ltd, (1991),Stevenage, UK, and specifically on page 34-36. Common catalysts forelectrolytic plating are conducting materials including metals and theconducting forms of carbon as discussed in “Fundamentals ofElectrochemical Deposition, Second Edition”, Milan Paunovic andMordechay Schlesinger, John Wiley & Sons, Inc., (2006).

In one embodiment the catalyst fraction comprises one or morecatalyst(s) selected from the group: (1) metal particles, includingpowders and colloids; (2) metal oxides; (3) organic metal complexes; (4)metal salts; (5) ceramics and other non-conductor powders coated withmetal salts, metal oxides, metal complexes, metal or carbon; and (6)carbon in all conductive forms; each metal of (1) to (5) selected fromthe group consisting of: Ag, Cu, Au, Fe, Ni, Al, Pd, Pt, Ru, Rh, Os, Ir,Sn and alloys thereof.

Examples of metal alloys useful as catalysts are stainless, carbon, low-and high-alloy steel; and alloys of nickel, copper, aluminum, magnesium,beryllium, titanium, zinc, molybdenum, tungsten, tin, lead, silver andmanganese. A comprehensive list of substrates can be found in Gawrilov,G. G.: Chemical (Electroless) Nickel Plating, Portcullis Press, Redhill,UK 1979; and Simon, H.: Galvanotechnik, 74 (1983) pp. 776-771.

In one embodiment, the catalyst is a conductive metal oxide selectedfrom doped and undoped metal oxide particles including transparentconductive oxides such as indium-tin-oxide (ITO), antimony-tin-oxide(ATO), tin oxide, fluorine-doped tin oxide, zinc oxide, aluminum-dopedzinc oxide (AZO), and zinc tin oxide (ZTO); alloys thereof.

In one embodiment the catalyst fraction comprises metal particles havingan average longest dimension of about 5 nm to about 1500 nm.

In another embodiment the catalyst fraction comprises one or moreorganic metal complexe(s). Examples of the organic metal complexes thatcan be used include acetylacetonatoplatinum, cis-bis(benzonitrile)dichloroplatinum, acetylacetonatopalladium,bis(benzylideneacetone)palladium, bis(benzonitrile)dichloropalladium,bis[1,2-bis(diphenylphosphino)ethane]palladium,hexafluoroacetyl-acetonatopalladium, etc.

In another embodiment the catalyst fraction comprises one or more metalsalts, for instance, palladium acetate and palladium chloride.

Platinum colloidal suspensions useful as catalysts can be prepared fromchloroplatinic acid (hydrogen hexachlorplatinate) as disclosed in Shah,P. et. al, Langmuir 1999, 15, 1584-1587. A commonly used palladiumcolloid is tetraoctadecylammonium bromide-stabilized palladium colloidas disclosed in Hidber, P. C. et. al., Langmuir 1996, 12, 5209-5215.

Adhesion Promoters

In various embodiments the catalyst transfer layer has an adhesionpromoter that is useful in improving the bonding of the patternedcatalyst layer to the base layer of the receiver after thermal transferis completed. The adhesion promoter also tends to improve the bonding ofthe patterned metal layer on the patterned substrate after plating iscompleted. With certain adhesion promoters, and typically with the glassfrit and metal oxides, additional treatment such as heating or annealingis required to realize optimal adhesion of the patterned catalyst layerand patterned metal layer to the substrate. In one embodiment thecatalyst layer comprises an adhesion promoter fraction of about 0.5 toabout 10 wt %, and preferably about 1.0 to about 4.0 wt %, based on thetotal weight of the catalyst layer.

Glass frit useful as an adhesion promoter usually has a softening pointof about 200 to 700° C., preferably about 350 to 700° C., morepreferably from 400 to 620° C. The glass frit useful as an adhesionpromoter typically has an average particle size of about 100 nm to about5 microns; and preferably about 100 nm to about 800 nm. However, glassfrit with an average particle size less than 100 nm can be used as anadhesion promoter, if so desired. The glass frit is suitably selectedfrom conventional glass frits having a softening point in the aboverange and then baked. Examples of the conventional glass frits include aglass frit with a low softening point in the above range comprising theoxides of the elements Al, Si, B, Na, Li, Ca, Mg, Mo, Ba, Bi, Zn, Zr,Ti, W, Sn, Sr, Co, Ru, V, Ta, W, Mn, Cu, Ag, Ce, Cd, and P. Specificglasses include PbO—SiO₂—B₂ O₃ glass, PbO—SiO₂—B₂ O₃—ZnO glass,PbO—SiO₂—B₂ O₃—Al₂ O₃—ZnO glass, B₂ O₃—SiO₂—B₂ O₃ glass, ZnO—SiO₂—B₂ O₃glass, and the like. These materials can be used independently or incombination as adhesion promoters. In one embodiment the adhesionpromoter fraction is 0.5 to about 10 wt %, preferably 1.0 to about 4.0wt %, based on the total weight of the catalyst layer, when glass fritis used.

Metal oxides useful as adhesion promoters can be, for example, Na₂O,CaO, CdO, BaO, ZrO, ZnO, MgO, CoO, NiO, FeO, MnO, PbO and combinationsthereof; and in combination with SiO₂.

Metal hydroxides and alkoxides useful as adhesion promoters includethose of Group IIIa thru VIIIa, Ib, IIb, IIIb, and IVb of the PeriodicTable and the lanthanides. Specific adhesion promoters are metalhydroxides and alkoxides of metals selected from the group consisting ofTi, Zr, Mn, Fe, Co, Ni, Cu, Zn, Al, and B. Preferred metal hydroxidesand alkoxides are those of Ti and Zr. Specific metal alkoxide adhesionpromoters are titanate and zirconate orthoesters and chelates includingcompounds of the formula (I), (II) and (III):

wherein

M is Ti or Zr;

R is a monovalent C₁-C₈ linear or branched alkyl;

Y is a divalent radical selected from —CH(CH₃)—, —C(CH₃)═CH₂—, or—CH₂CH₂—;

X is selected from OH, —N(R¹)₂, —C(O)OR³, —C(O)R³, —CO₂ ⁻A⁺; wherein

R¹ is a —CH₃ or C₂-C₄ linear or branched alkyl, optionally substitutedwith a hydroxyl or interrupted with an ether oxygen; provided that nomore than one heteroatom is bonded to any one carbon atom;

R³ is C₁-C₄ linear or branched alkyl;

A⁺ is selected from NH₄ ⁺, Li⁺, Na⁺, or K⁺.

In one embodiment the adhesion promoter fraction is about 0.5 to about20 wt %, preferably about 0.5 to about 5.0 wt %, based on the totalweight of the catalyst layer, when metal hydroxides and alkoxides areused as the adhesion promoter fraction. Commercially available titanateand zirconate orthoesters and chelates useful as adhesion promoters arethe TYZOR® organic titanates and zirconates available from E.I. DuPontde Nemours, Inc., Wilmington, Del. Specific organic zirconates areTYZOR® 212, 217, TEAZ, and Cl-24 organic zirconates. Specific organictitanates are TYZOR® TE and LA organic titanates.

Silicate hydroxides and alkoxides useful as adhesion promoters includethose of formula (IV)(R¹¹O)_(4-m)Si(R¹²)_(m)

wherein

-   -   m is an integer equal to 0, 1, 2, or 3;    -   R¹¹ is hydrogen or a C₁-C₆ linear or branched alkyl; and    -   R¹² is a C₁-C₁₂ linear or branched alkyl, optionally having 1 or        2 carbon-carbon double bonds, and optionally substituted by        —NH₂; —CN, —NCO, or —OC(O)—CR¹³═CH₂; wherein R¹³ is hydrogen or        C₁-C₄ alkyl.

Specific examples of silicate alkoxides useful in the invention aretetramethoxysilane; tetraethoxysilane, tetrapropoxysilane,tetrabutoxysilane, trimethoxymethylsilane, triethoxymethylsilane,trimethoxyvinylsilane, triethoxyvinylsilane, 3-aminopropyltrimethoxysilane, 3-aminopropyl triethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyl triethoxysilane,3-isocyanatopropyl trimethoxysilane, 3-isocyanatopropyl triethoxysilane,and 3-cyanopropyl trimethoxysilane.

In one embodiment the adhesion promoter fraction is about 0.5 to about20 wt %, preferably about 0.5 to about 5.0 wt %, based on the totalweight of the catalyst layer, when silicate hydroxides and alkoxides areused as the adhesion promoter fraction.

Organic polyols useful as adhesion promoters include organic polyolshaving two or more hydroxyl groups per molecule and having hydroxylequivalent weights of about 30 to about 200 g/equivalent, preferablyabout 30 to about 100 g/equivalent, and more preferably about 30 toabout 60 g/equivalent. In one more specific embodiment the organicbinders useful as adhesion promoters are organic polyols selected fromthe group consisting of C₂-C₆₀ linear or branched alkyl; C₅-C₆₀alicyclic; and C₆-C₆₀ radicals consisting of a combination of linear orbranched alkyl and alicyclic radicals; each optionally interrupted byone or more —O—, —S—, —OC(O)—, and —NR¹¹C(O)—, wherein R¹¹ is hydrogenor a C₁-C₆ linear or branched alkyl. In one embodiment, the adhesionpromoter fraction can contain at least one polyol selected from ethyleneglycol, glycol derivatives, glycerol and glycerol derivatives,pentaerythritol (CAS [115-77-5]), trimethylolpropane (CAS [77-99-6]),dipentaerythritol (CAS [126-58-9]), ditrimethylolpropane (CAS[23235-61-2]), sorbitol (CAS 50-70-4]), sorbitan monooleate (CAS[1338-43-8]), sorbitan monolaurate (CAS [1338-39-2]), 2-butyl 2-ethyl1,3-propanediol (CAS 115-84-4]), 2-methyl 1,3-propanediol (CAS[2163-42-0]), neopentyl glycol (CAS [126-30-7]), 1,4-butanediol (CAS[110-63-4]), and 1,6-hexanediol (CAS [629-11-8]).

In one embodiment, organic binders useful as the adhesion promoterfraction can contain at least one of an ethoxylated or propoxylatedcompound such as ethoxylated pentaerythritol (CAS [42503-43-7]),propoxylated pentaerythritol (CAS [9051-49-4]), ethoxylated trimethylolpropane adducts, e.g. those equivalent to ethoxylation with 3-8 moles ofethylene oxide per mole ingredient (CAS [50586-59-9]), ethoxylatedtrimethylol propane propylene oxide adducts equivalent to propyleneoxide at 3 to 9 mole equivalents per mole ingredient (CAS [25723-16-4]),ethoxylated sorbitan monooleate equivalent to ethylene oxide adduct withfrom 20 to 80 ethylene oxide moles per mole ingredient (CAS[9005-65-6]), and ethoxylated sorbitan monolaurate (CAS [9005-64-5]).

In one embodiment, the organic binders useful as adhesion promoterfraction can contain a hyperbranched polyol, for example a dendritichyperbranched polyol, a hyperbranched dendritic polyether or polyester,a hyperbranched polyether or polyester, arborols, dendritic or cascadesuper-molecules and their hyperbranched cousins, or a dendriticmacromolecule of the polyester type having one or more reactive hydroxylgroups. Such hyperbranched polyols are described for example in U.S.Pat. No. 5,418,301 of Hult, et al. assigned to Perstorp AB titled“Dendritic Macromolecule and Process for Preparation Thereof”, U.S. Pat.No. 5,663,247 of Sorensen et al. assigned to Perstorp AB titled“Hyperbranched Macromolecule from Epoxide Nucleus and Hydroxy-functionalCarboxylic Acid Chain Extenders”, U.S. Pat. No. 6,617,418 of Magnussonet al. assigned to Perstorp AB titled “Hyperbranched Dendritic Polyetherand Process for Manufacture Thereof”, and U.S. Pat. No. 6,765,082 ofSunder et al. assigned to Bayer Aktiengesellschaft titled “Method forProducing Highly-Branched Glycidol-based Polyols”. Commerciallyavailable hyperbranched polyol products include those of Perstorp, forexample Boltorn H20, H2003, H2004, H30, H40, P1000, and H311 withrespective average OH functionality per molecule of 16, 12, 6.4, 32, 64,14, and unspecified, and respective average relative molecular mass of2100, 2500, 3200, 3500, 5400, 1500, and unspecified. Examples ofhyperbranched polyols include polyether structure (V) and polyesterstructure (VI) based upon pentaerythritol:

In one embodiment, the organic binders useful as adhesion promoterfraction can contain branched alkyl interrupted by —O—, —S—, —OC(O)—,and —NR¹¹C(O)—. Specific examples of polyols interrupted by —OC(O)—, arelisted above. A specific example of an polyol interrupted by —NR¹¹C(O)—,referred to amide polyols, is formula (VII), commercially available asPRIMID® XL552 polyol from EMS Chemie, Domat/Ems, Switzerland.

In one embodiment the adhesion promoter fraction is about 0.5 to about20 wt %, preferably about 0.5 to about 5.0 wt %, based on the totalweight of the catalyst layer, when organic polyols are used as theadhesion promoter fraction.

Polymer Binder Fraction

The catalyst layer, optionally, and independently of whether an adhesionpromoter is present, has a polymer binder fraction. In one embodimentthe catalyst layer has a polymer binder fraction and, preferably, thepolymer binder is selected from the group consisting of: one or moreconducting (co)polymers/(co)oligomers selected from the group consistingof: polyaniline, polythiophene, polypyrrole, polyheteroaromaticvinylenes, and their derivatives; one or more non-conducting(co)polymers/(co)oligomers selected from the group consisting of:acrylic, styrenic and styrenic-acrylic latexes; solution-based acrylic,styrenic and styrenic-acrylic polymers; and combinations thereof;copolymers of ethylene with one or more monomers selected from the groupconsisting of: alkyl (meth)acrylate(s) wherein the alkyl group is a C1to C18 linear or branched chain alkyl, norbornene, vinyl acetate, carbonmonoxide, (meth)acrylic acid; and polyvinylacetate and its copolymers;vinyl (co)polymer(s) or (co)oligomer(s) comprising repeat units selectedfrom the group consisting of: vinyl acetate, vinyl chloride,vinylbutyraldehyde, vinyl alcohol and vinylpyrrolidone;heteroatom-substituted styrenic polymers selected from the groupconsisting of: poly(4-vinyl)pyridine, poly(4-hydroxy)styrene, partiallyhydrogenated poly(4-hydroxy)styrene, and copolymers thereof;phenol-aldehyde (co)polymers and (co)oligomers and combinations thereof.

In one embodiment polymer binder fraction comprises polymers selectedfrom the group consisting of: acrylic and styrenic-acrylic latexes andsolution-based acrylic and styrenic-acrylic (co)polymers includingrandom and graft copolymers; and combinations thereof; copolymers ofethylene with one or more monomers selected from the group consistingof: (meth)acrylates, vinyl acetate, carbon monoxide and (meth)acrylicacid; polyvinylacetate and its copolymers; and polyvinylpyrrolidone andits copolymers including polyvinylpyrrolidone-co-vinyl acetate.Preferably the latexes have an average particle size of less than about150 nm, more preferably, less than about 100 nm. Preferredsolution-based acrylic, styrenic and styrenic-acrylic polymers have aM_(w) of less than about 100,000, preferably less than 50,000, and morepreferably less than 30,000. In one embodiment the polymer binderfraction has an acid number of about 10 to about 300. The acid number isthe milli-equivalents of KOH per gram, as determined by standardtitration techniques, needed to neutralize the acid functionality in thelatex or solution polymers. The acid functionality is generallyincorporated into the acrylic and styrenic-acrylic polymers bycopolymerization of ethyleneically unsaturated carboxylic acids, such asacrylic acid, methacrylic acid, etc. Commercial examples ofsolution-based acrylic and styrenic acrylic polymers useful as polymerbinders include Carboset® GA2300 (Noveon), Joncryl® 63 (JohnsonPolymer), and Elvacite® 2028 (Lucite International). Commercial examplesof acrylic and styrenic acrylic latexes useful as polymer bindersinclude Joncryl® 95, 538 and 1915 (co)polymers (Johnson Polymer).Methods for synthesizing suitable latex polymers have been reported inWO 03/099574.

In one embodiment the catalyst layer and patterned catalyst layercomprises about 1.0 to 99 wt % catalyst fraction; about 0.5 to 10 wt %adhesion promoter fraction; and about 0.5 to 98.5 wt % polymer binderfraction.

Another embodiment includes a catalyst transfer layer comprising anadhesion promoter fraction comprising organic polyols and a polymerbinder fraction comprising acrylic and styrenic-acrylic latexes andsolution-based acrylic and styrenic-acrylic (co)polymers having an acidnumber less than about 250; preferably less than about 100. Preferablythe organic polyols are amide polyols, as discussed above.

Antireflective Agent Fraction

When the patterned metal layer provided by the invention is to be usedin display applications, for instance, as the front filter for a displaydevice, the catalyst layer, optionally and preferably, has anantireflective agent fraction designed to reduce the reflectivity of thecatalyst layer, and the metal layer plated onto it. In specificembodiments the antireflective agent is a black pigment selected fromthe group consisting of ruthenium, manganese, nickel, chromium, iron,cobalt, copper, and alloys thereof; their oxides; and mixtures thereof.Preferred antireflective agents include RuO₂, Cr₃O₄, CO₂O₃, and Ni.Examples of nonconductive antireflective agents are ceramic-based blacksincluding Fe—Co chromite, Cr—Fe—Ni spinel, and Cu-chromite. When thecatalyst layer contains an antireflective agent fraction, theconductivity of the catalyst layer often decreases. Therefore, it isdesirable to control the amount of an antireflective agent. In anotherembodiment the antireflective agent can be a reactive precursor, whichupon treatment provides the antireflective agent. Examples of a reactiveprecursors to antireflective agents include metals such as ruthenium,manganese, nickel, chromium, iron, cobalt, or copper; alkoxidederivatives, complexes with β-diketones, complexes with β-keto acidesters, and organic carboxylate esters of these metals. They areconverted to the corresponding oxides on baking to exhibit black colorand antireflective properties. When the metal as such is used as areactive precursor to the antireflective agent, it may be different fromthe metal powder used as the catalyst fraction, or one metal may havethe dual functions. For example, when copper powder is used as thecatalyst fraction, a part of the copper powder may become black copperoxide on baking.

Another embodiment of the invention is a thermal transfer donorcomprising a base film, a catalyst layer (A), and a LTHC layerinterposed between said base film and said catalyst layer (A), saidcatalyst layer (A) comprising:

-   -   (i) about 1.0 to about 99 wt % of a catalyst fraction, based on        the total weight of the catalyst layer, said catalyst fraction        comprising metal particles selected from Ag, Cu, and alloys        thereof;    -   (ii) about 0.5 to about 10 wt % of an adhesion promotor fraction        selected from glass frit; and metal hydroxides and alkoxides;    -   (iii) about 0.5 to about 98.5 wt % of a polymer binder.

Another embodiment is the thermal transfer donor as described abovewherein the catalyst layer (A) consists essentially of components (i),(ii), and (iii), as described above; wherein the polymer binder isselected from the group consisting of: one or more conducting(co)polymers/(co)oligomers selected from the group consisting of:polyaniline, polythiophene, polypyrrole, polyheteroaromatic vinylenes,and their derivatives; one or more non-conducting(co)polymers/(co)oligomers selected from the group consisting of:acrylic, styrenic and styrenic-acrylic latexes; solution-based acrylic,styrenic and styrenic-acrylic polymers; and combinations thereof;copolymers of ethylene with one or more monomers selected from the groupconsisting of: alkyl (meth)acrylate(s) wherein the alkyl group is a C1to C18 linear or branched chain alkyl, norbornene, vinyl acetate, carbonmonoxide, (meth)acrylic acid; and polyvinylacetate and its copolymers;vinyl (co)polymer(s) or (co)oligomer(s) comprising repeat units selectedfrom the group consisting of: vinyl acetate, vinyl chloride,vinylbutyraldehyde, vinyl alcohol and vinylpyrrolidone;heteroatom-substituted styrenic polymers selected from the groupconsisting of: poly(4-vinyl)pyridine, poly(4-hydroxy)styrene, partiallyhydrogenated poly(4-hydroxy)styrene, and copolymers thereof;phenol-aldehyde (co)polymers and (co)oligomers and combinations thereof.

Another embodiment is a thermal transfer donor wherein the LTHC layercomprises one or more radiation absorbers selected from the groupconsisting of: metal films selected from Cr and Ni; carbon black;graphite; and near infrared dyes with an absorption maxima in the rangeof about 600 to 1200 nm within the LTHC layer.

Another embodiment is a thermal transfer donor wherein the LTHC layercomprises: one or more water-soluble or water-dispersibleradiation-absorbing cyanine compound(s) selected from the groupconsisting of: indocyanines, phthalocyanines, and merocyanines; and oneor more water-soluble or water-dispersible polymeric binders selectedfrom the group consisting of: acrylic resins, hydrophilic polyesters,sulphonated polyesters and maleic anhydride homopolymers and copolymers.

The thermal transfer donor may have one or more additional transferlayers disposed on a side of the catalyst transfer layer opposite saidbase film, herein defined as above the metal transfer layer. Theadditional transfer layer thickness can be anywhere from about 5 nm toabout 5 μm, and more preferably, about 100 nm to about 3 μm. Theadditional transfer layer can be a functional layer, acting as aconducting, semiconducting, insulating, adhesive, planarizing, lightattenuating or protective layer, for instance, and is transferred alongwith the metal transfer layer in the thermal transfer process. Followingtransfer, the additional transfer layer will be disposed between thepatterned catalysis layer and the base layer of the receiver.

Another embodiment is a thermal transfer donor comprising, in layeredsequence, a base film, a catalyst transfer layer (B) and an adhesionpromoter layer, said catalyst transfer layer (B) comprising:

-   -   (ii) about 1.0 to about 99 wt % of a catalyst fraction, based on        the total weight of the catalyst layer, said catalyst fraction        comprising metal particles selected from Ag, Cu, and alloys        thereof;    -   (iii) about 1.0 to about 99 wt % of a polymer binder; and        wherein the adhesion promoter layer comprises material selected        from glass frit; and metal hydroxides and alkoxides.

Another embodiment is a thermal transfer donor comprising, in layeredsequence, a base film, a catalyst layer (B) and an adhesion promoterlayer, said catalyst layer (B) consisting essentially of components (i)and (iii), as described above; wherein the polymer binder is selectedfrom the group consisting of: one or more conducting(co)polymers/(co)oligomers selected from the group consisting of:polyaniline, polythiophene, polypyrrole, polyheteroaromatic vinylenes,and their derivatives; one or more non-conducting(co)polymers/(co)oligomers selected from the group consisting of:acrylic, styrenic and styrenic-acrylic latexes; solution-based acrylic,styrenic and styrenic-acrylic polymers; and combinations thereof;copolymers of ethylene with one or more monomers selected from the groupconsisting of: alkyl (meth)acrylate(s) wherein the alkyl group is a C1to C18 linear or branched chain alkyl, norbornene, vinyl acetate, carbonmonoxide, (meth)acrylic acid; and polyvinylacetate and its copolymers;vinyl (co)polymer(s) or (co)oligomer(s) comprising repeat units selectedfrom the group consisting of: vinyl acetate, vinyl chloride,vinylbutyraldehyde, vinyl alcohol and vinylpyrrolidone;heteroatom-substituted styrenic polymers selected from the groupconsisting of: poly(4-vinyl)pyridine, poly(4-hydroxy)styrene, partiallyhydrogenated poly(4-hydroxy)styrene, and copolymers thereof;phenol-aldehyde (co)polymers and (co)oligomers and combinations thereof.

The adhesion promoter layer in the embodiments described abovepreferably comprises material selected from glass frit; and metalhydroxides and alkoxides, as described above. In another embodiment theadhesion promoter layer further comprises a polymer binder selected fromthe group consisting of: one or more (co)polymers/(co)oligomers selectedfrom the group consisting of: acrylic, styrenic and styrenic-acryliclatexes; solution-based acrylic, styrenic and styrenic-acrylic polymers;and combinations thereof; copolymers of ethylene with one or moremonomers selected from the group consisting of: alkyl (meth)acrylate(s)wherein the alkyl group is a C1 to C18 linear or branched chain alkyl,norbornene, vinyl acetate, carbon monoxide, (meth)acrylic acid; andpolyvinylacetate and its copolymers; vinyl (co)polymer(s) or(co)oligomer(s) comprising repeat units selected from the groupconsisting of: vinyl acetate, vinyl chloride, vinylbutyraldehyde, vinylalcohol and vinylpyrrolidone; heteroatom-substituted styrenic polymersselected from the group consisting of: poly(4-vinyl)pyridine,poly(4-hydroxy) styrene, partially hydrogenated poly(4-hydroxy)styrene,and copolymers thereof; phenol-aldehyde (co)polymers and (co)oligomersand combinations thereof.

Another embodiment is the thermal transfer donor comprising an adhesionpromoter layer, as described above, wherein the adhesion promoter layerfurther comprises an antireflective agent fraction, as disclosed above,designed to reduce the reflectivity of the adhesion promoter layer. Theadhesion promoter layer comprising an antireflective agent fraction canbe deposed on top of the catalyst transfer layer as an additionaltransfer layer.

Optionally, a protective strippable cover sheet may be present on theoutmost layer of the thermal transfer donor. The cover sheet protectsthe underlaying transfer layers and is easily removable.

The thermal imaging donor comprising a catalyst transfer layer may beprepared by applying a fluid dispersion of the catalyst transfer layercomposition onto the surface of a base film, or the LTHC layer, ifpresent, and volatizing the carrier fluid. Applying the fluid dispersioncan be accomplished by any method that gives a uniform layer, or ifdesired, a patterned or nonuniform catalyst transfer layer. Coating,including rod coating and spin-coating, spraying, printing, blading orknifing can be used. Coating and spraying are preferred methods forapplying the fluid dispersion to provide uniform catalyst transferlayers. The carrier fluid is allowed to evaporate to provide thecatalyst transfer layer or the layer can be dried by any conventionalmethod of drying including applying heat and/or vacuum.

Receiver

The thermal imaging method requires the presence of a thermal imagingreceiver to receive the patterned catalyst layer. FIG. 2A is across-sectional view of thermal imaging receiver 200 having a receiverbase layer 202. The receiver base layer 202 is a dimensionally stablesheet material as defined for the base film of the thermal transferdonor. Additionally, the receiver base layer can be an opaque material,such as polyethylene terephthalate filled with a white pigment such astitanium dioxide; ivory paper; or synthetic paper, such as Tyvek®spunbonded polyolefin. The base layer material can also be glass.Preferred base layers for receivers are polyethylene terephthalate,polyethylene naphthalate, polyimide, for instance Kapton® polyamide, andglass.

In another embodiment the thermal imaging receiver may comprise one ormore optional additional layers, such as an adhesive layer; anantireflective layer; etc., which may be a continuous layer over thebase layer or a patterned layer. A particular useful receiveradditionally comprises a patterned antireflective layer 204, asillustrated in FIG. 2B. The patterned antireflective layer can be madeusing a similar thermal imaging process as disclosed below. Suitableantireflective layers include one or more nonconductive materialsselected from the group consisting of: RuO₂, cobalt oxide, nickel oxide,iron-cobalt chromite, copper chromite, and non-conductive carbon blacks.

Contacting

The thermal transfer donor is contacted with a thermal imaging receiver.The contacting may occur with the catalyst transfer layer of the donor;or with any optional layers that overlay the catalyst transfer layer. By“contacting” is meant that the donor is in close proximity, preferablywithin several microns of the receiver. The receiver may be off-set fromthe donor by, for example, previously printed layers, fibers orparticles that act as spacers to provide a controlled gap between donorand receiver. Vacuum and/or pressure can be used to hold the donorelement 100 and the receiver element 200 together. As one alternative,the donor element 100 and the receiver element 200 can be held togetherby fusion of layers at the periphery of the assembly. As anotheralternative, the donor element 100 and receiver element 200 can be tapedtogether and taped to the imaging apparatus. A pin/clamping system canalso be used. As yet another alternative, the donor element can belaminated to the receiver element. If the donor element 100 and thereceiver element 200 are flexible, the assembly can be convenientlymounted on a drum to facilitate laser imaging.

Transferring

Thermal transfer can be achieved by a laser-mediated transfer process asillustrated in FIG. 3. In one embodiment, the assembly of the donor 100and the receiver 200 is selectively exposed to heat, which is preferablyin the form of laser radiation (R), in an exposure pattern of the imageof the desired pattern to be formed on the receiver. The laser radiationor laser beam (R) is focused about at the interface between the catalysttransfer layer 106 and LTHC layer 108, if present, otherwise it isfocused about at the interface between 106 and base film 102. Sufficientradiation is applied to achieve transfer of the catalyst layer to thereceiver.

A variety of light-emitting sources can be used to heat the thermaltransfer donor elements. For analog techniques (e.g., exposure through amask), high-powered light sources (e.g., xenon flash lamps and lasers)are useful. For digital imaging techniques, infrared, visible, andultraviolet lasers are particularly useful. Other light sources andirradiation conditions can be suitable based on, among other things, thedonor element construction, the transfer layer material, the mode ofthermal transfer, and other such factors.

The radiation is preferably applied through the backside of base film102, that is, the side not containing the catalyst transfer layer. Laserradiation preferably is provided at a laser fluence of up to about 600mJ/cm², and more preferably about 75-440 mJ/cm². Lasers with anoperating wavelength of about 350 nm to about 1500 nm are preferred.Particularly advantageous are diode lasers, for example those emittingin the region of about 750 to about 870 nm and up to 1200 nm, whichoffer a substantial advantage in terms of their small size, low cost,stability, reliability, ruggedness and ease of modulation. Such lasersare available from, for example, Spectra Diode Laboratories (San Jose,Calif.). One device used for applying an image to the receiver is theCreo Spectrum Trendsetter 3244F, which utilizes lasers emitting near 830nm. This device utilizes a Spatial Light Modulator to split and modulatethe 5-50 Watt output from the ˜830 nm laser diode array. Associatedoptics focus this light onto the imageable elements. This produces 0.1to 30 Watts of imaging light on the donor element, focused to an arrayof 50 to 240 individual beams, each with 10-200 mW of light inapproximately 10×10 to 2×10 micron spots. Similar exposure can beobtained with individual lasers per spot, such as disclosed in U.S. Pat.No. 4,743,091. In this case each laser emits 50-300 mW of electricallymodulated light at 780-870 nm. Other options include fiber-coupledlasers emitting 500-3000 mW and each individually modulated and focusedon the media. Such a laser can be obtained from Opto Power in Tucson,Ariz.

Suitable lasers for thermal imaging include, for example, high power(>90 mW) single mode laser diodes, fiber-coupled laser diodes, anddiode-pumped solid state lasers (e.g., Nd:YAG and Nd:YLF). Laserexposure dwell times can vary widely from, for example, a few hundredthsof microseconds to tens of microseconds or more, and laser fluences canbe in the range from, for example, about 0.01 to about 5 J/cm² or more.

The thermal imaging method requires at least a portion of the catalysttransfer layer be transferred onto the thermal imaging receiver bythermal transfer to provide a patterned catalyst layer on the receiverbase film. The patterned catalyst layer on the receiver base filmbecomes, upon removal of the spent thermal imaging donor, the patternedsubstrate, required for the plating step.

In another embodiment of the method, the donor further comprises, on thecatalyst transfer layer opposite the base film, an adhesion promoterlayer; and said transferring further comprises transferring acorresponding proximate portion of the adhesion promoter layer toprovide said patterned substrate having, in layered sequence on thereceiver, a patterned adhesion promoter layer and said patternedcatalyst layer. Preferred adhesion promoter layers comprise materialsselected from glass frit, metal hydroxides and metal alkoxides. The term“transferring a corresponding proximate portion of the adhesion promoterlayer together” means that the transference of the exposed catalysttransfer layer onto the receiver includes a simultaneous matchingtransference of the exposed adhesion promoter layer, residing adjacentthe catalyst transfer layer, onto the receiver. In embodiments whereinthe catalyst transfer layer comprises more than one layer or additionaltransfer layers are present on top of the catalyst transfer layer, theselayers are transferred in a like manner.

In another embodiment of the method the adhesion promoter layer furthercomprises an antireflective agent fraction, as disclosed above.

After exposure, the donor element 100 and the receiver element 200 areseparated, as illustrated in FIGS. 4A and B, leaving the untransferredportions of the catalyst transfer layer 106 on the donor element 100 andthe patterned catalyst layer on the receiver element 200. Usually theseparation of the donor and receiver is achieved by simply peeling thetwo elements apart. This generally requires very little peel force andis accomplished by simply separating the donor element from the receiverelement. This can be done using any conventional separation techniqueand can be manual or automatic.

Another embodiment is a thermal imagining method wherein the receiveradditionally comprises a patterned anti-reflective layer having limits;and said transferring at least a portion of the catalyst transfer layeronto the receiver, is within the limits of the patterned anti-reflectivelayer. This is another useful method allowing darkening of the patternedcatalyst layer. The patterned anti-reflective layer can be deposed onthe receiver base layer in a preliminary imaging process; followed bytransferring of the patterned catalyst layer; in registration with thepatterned anti-reflective layer.

Usually the transferred portions of the transfer layers correspond tothose portions of the transfer layers exposed to laser radiation. Insome instances, depending upon the nature of the donor and receiverelements and the transfer processing parameters, when the donor element100 and the receiver element 200 are separated, the receiver elementincludes both exposed portions and non-exposed portions of one or moretransfer layers. A process for enhancing the resolution of a pattern ona thermal imaging receiver comprising an exposed portion and anon-exposed portion of one or more thermal transfer layers on a surfaceof the thermal imaging receiver comprises: (a) contacting said surfaceof the thermal imaging receiver with an adhesive surface to provide atemporary laminate; and (b) removing said adhesive surface from thetemporary laminate to provide a thermal imaging receiver with a surfacesubstantially free of said non-exposed portion of one or more transferlayers. Suitable adhesive surfaces for performing the process arecommercial adhesive tapes, for instance, those Scotch® brand tapesavailable from 3M company. Tacky rollers, for instance, a medium tackroller available in the form of a Dust Removal System-1 (red) from SDI(Systems Division, Inc., Irvine, Calif. 92618-2005) are a suitableadhesive surface for the process. Chrome films, used as LTHC layersdescribed above, also make useful low tack adhesive layers for removingnon-exposed portions of the transfer layers under very gentleconditions.

Another embodiment of the thermal imaging method further comprises:

(d) heating the patterned substrate to an anneal temperature for ananneal period to provide the annealed patterned substrate; and saidplating metal, comprises plating said annealed patterned substrate. Thisaspect of the thermal imaging method is useful in fixing the adhesionpromoter, present in or adjacent the patterned catalyst layer, to thereceiver. Annealing of the patterned substrate is particularly useful inprocesses wherein the patterned metal layer provided by the plating stepis intended to remain bonded to base layer. Glass frit is typicallyheated to a softening or melting temperature as disclosed above. Otheradhesion promoters such as the polyols combined with polycarboxylates,metal hydroxides and alkoxides, can also give improved adhesion tosubstrates upon heating to an anneal temperature. For polymer baselayers, the anneal temperature is usually between 80 and 150° C.; forglass base layers, the anneal temperature can be higher, typically 150to 550° C. depending upon whether polymer binders are present in thepatterned catalyst layer and the particular nature of the adhesionpromoter.

Plating

The method further comprises plating metal onto said patternedsubstrate, to provide the patterned metal layer in connectivity with thepatterned catalyst layer. Herein the term “plating” refers to any methodproviding selective metal deposition onto the patterned catalysis layer,as a result of the presence of the patterned catalyst layer. Wet platingis preferable since the metal layer can be selectively formed on thepatterned catalyst layer. Wet plating includes electroless plating andelectrolytic plating, or a combination thereof, and is adequatelyselected depending on the required conductivity of the patternedcatalyst layer. Electrolytic plating is a galvanic process requiring anelectric current to be passed through an electrolyte solution containingmetal ions capable of being reduced. The most common electrolyticplating system involves a conducting substrate as an anode (thesubstrate undergoing plating); a chemical solution containing an ionicform of the metal to be plated; and a cathode where electrons are beingsupplied to produce a film of metal. Electroless plating is anon-galvanic plating that involves several simultaneous chemicalreactions in an aqueous solution, which occur without the use ofexternal electrical power. Electroless plating systems have in common ametal ion capable of being reduced to a metal; and a chemical reducingagent capable of delivering electrons to the metal ion. The most commonelectroless plating method is electroless nickel plating that usessodium hypophosphite as the reducing agent and nickel (II) ions as themetal ion. The two plating processes may be employed in combination.When the patterned catalyst layer is conductive, the electroplating canbe applied from the beginning. When conductivity of the pattern isinsufficient, a first conductive layer having a small thickness isformed by electroless plating; and then, a second conductive layer isformed by electroplating; to from the patterned metal layer. Oneembodiment of the invention is wherein the plating metal is selectedfrom the group consisting of Ni, Cu, Fe, Cr, Sn, Mn, Mo, Ag, Au, W, Zn,and alloys thereof. Preferred plating metals are Ni and Cu.

The plating process may further include any treatment processes that areknown in the art of plating that may be beneficial in the overalldeposition of metal onto the patterned catalyst layer. For instance, thepatterned substrates may be pre-treated with sensitizers, cleaningagents, and the like before the deposition of metal.

The patterned metal layer provided by the plating process may be asingle layer or a multilayer having two, three or more sub-layers. Thethickness of the patterned metal layer is usually from about 0.1 toabout 20 microns, preferably from about 0.1 to about 5 microns. In oneembodiment the patterned metal layer has a resistivity of less than 0.2Ohms per square as measured using the 4 probe resistance function of aHP 3478A multimeter. Preferably the patterned metal layer is in the formof a geometric pattern of lines forming a mesh having pitches in therange of 150 to 500 micron, and a line width of about 10 to 80 microns.

Darkening Agent

In another embodiment, the method further comprises treating thepatterned metal layer with a darkening agent to provide a darkenedpatterned metal layer to reduce reflectivity of the metal layer, asevidenced by visual examination. The darkening agent can be an oxidizingagent that oxidizes metals like Cu, Ni and alloys thereof. For instance,EBONOL®-C oxidizer, is a proprietary blackening agent for copper andcopper alloys marketed by Cookson Electronics, Providence, R.I.; that isuseful as a darkening agent in the treating of the patterned metallayer.

FIG. 5 is a side-view of one embodiment encompassing a receiver 200including a receiver base layer 202, patterned antireflective layer 204,a patterned catalyst layer 106, a patterned metal layer 210, and adarkened patterned metal layer 212.

Electronic Device

Another embodiment is an electronic device having a patterned metallayer on a substrate, said substrate substantially transparent tovisible light; said patterned metal layer comprising in layered sequenceon said substrate, an adhesion promoter layer, a catalyst layer, and aplated metal layer; and said patterned metal layer having a pattern withat least one line of width of about 1 millimeter or less. Preferably thepatterned metal layer has at least at least one line of width of about200 microns or less. In other embodiments the patterned metal layer hasat least one line of width of about 150 microns or less, 100 microns orless, 50 microns or less, 20 microns or less and 10 microns or less. Inanother embodiment of the electronic device, the adhesion promoter layercomprises material selected from glass frit, and metal hydroxides andalkoxides; and the catalyst layer comprises (i) about 0.5 to about 99 wt% of a catalyst fraction, based on the total weight of the catalystlayer, said catalyst fraction comprising metal particles selected fromAg, Cu, and alloys thereof; and (ii) about 0.5 to about 99 wt % of apolymer binder.

Another embodiment is an electronic device, as disclosed above, whereinthe adhesion promoter layer further comprises an antireflective agentfraction. Preferred antireflective agents are as disclosed above.

Another embodiment is an electronic device, as disclosed above, whereinthe adhesion promoter layer further comprises an antireflective agentfraction; and the patterned metal layer further comprises anantireflective layer on the metal layer opposite the adhesion promoterlayer.

Preferred embodiments of the electronic device, as disclosed above,include a touchpad sensor and an electromagnetic interference (EMI)shield.

A touchpad sensor comprising a patterned metal layer as described abovefurther comprises a dielectric layer, typically an organic polymerhaving suitable dielectric properties. In one embodiment the touchpadsensor comprises a first base layer with a first patterned metal layer;a second base layer with a second patterned metal layer; and adielectric layer deposed between the first and second patterned metallayers. In another embodiment the touchpad sensor comprises a first baselayer, having two opposing surfaces, a patterned metal layer deposed oneach of the two opposing surfaces; and a dielectric layer on top of eachof the patterned metal layers.

The various embodiments of the method have several advantages over othermethods for producing metal patterns, including precise digital controlof the pattern being formed; the capability to prepare mesh having finelines, down to 10 micron line-width; and the capability to depose otherlayers, such as antireflective layers, adhesive layers, dielectriclayers, etc., in a precise relation to the metal pattern. In additionthe steps of manufacturing the patterned catalyst layer are dry steps,that is, they do not require the use of solvents, etchants, and masks,typically used in conventional photolithography methods. The only steprequiring conventional “wet” processing is the plating step. Thus, theoverall method may be more environmental friendly than conventionalmethods used in making metal mesh.

Materials, Equipment and Methods

Unless otherwise indicated, chemicals were used as received withoutfurther purification. Polymers, plasticizers, IR dyes, and surfactantswere obtained from the sources listed in the specification or purchasedfrom Aldrich. Pigments such as carbon black dispersions were obtainedfrom Penn Color, Inc., Doylestown, Pa. Silver nanoparticles werepurchased from Ferro Co.—Electronic Material Systems, Cleveland, Ohio;Nanostructured & Amorphous Materials, Inc., and Mitsui Co.

A Flatbed printer was used for transferring catalyst transfer layersonto glass substrates. The imaging head used was a SQUAREspot® thermalimaging head manufactured by Creo/Kodak, Vancouver, Canada. The head wasmounted on the flatbed scanner as described in the paper “ThermalTransfer for Flat Panel Display Manufacturing”, Eran Elizur and DanGelbart, Journal of the Society for Information Display, Vol. 11 Number1, pp. 199-202.

A Creo Trendsetter® 800 (Creo/Kodak, Vancouver, Canada) was utilized forimaging to flexible substrates. The Creo Trendsetter® 800 is a modifieddrum-type imager utilizing a modified Thermal 1.7 Head with a 12.5 wattmaximum average operating power at a wavelength of 830 nm with 5080 dpiresolution. The 800 Trendsetter was operated in a controlledtemperature/humidity environment with an average temperature of ˜68° C.and an average relative humidity of ˜40-50%. For each printingexperiment, a section of thermal imaging receiver was positioned on thedrum. The thermal transfer donor was loaded so that the side of thedonor element coated with the catalyst transfer layer was facing thefree side of the receiver. Imaging assemblages were exposed from theback-side through the donor film base. Films were mounted using vacuumhold down to a standard plastic or metal carrier plate clampedmechanically to the drum. In some experiments utilizing the CreoTrendsetter® 800 thermal platesetter, a nonstandard drum with vacuumholes machined directly onto the drum to match common donor and receiversizes was used as a replacement for the standard drum/carrier plateassemblage. Contact between the donor and receiver was established byabout 600 mm of Hg vacuum pressure. Laser output was under computercontrol to build up the desired image pattern. Laser power and drumspeed were controllable and were adjusted in an iterative fashion tooptimize image quality as judged by visual inspection of the transferredimage on the receiving surface.

Method 1: Thermal Transfer onto Rigid Substrates

A glass panel, acting as the receiver base layer, was cleaned usingMicro 90, a cleaning solution manufactured by International Products,Corp., Burlington, N.J., treated with UVO (UVO is a process where asurface is exposed to deep UV light (185 nm-254 nm) having an intensityof ˜30 mJ/sec cm² in the presence of air) for abut 5 min and then rinsedin DI water. A thermal transfer donor was placed in vacuum contact witha receiver on a flatbed scanner as described in the paper “ThermalTransfer for Flat Panel Display Manufacturing”, Eran Elizur and DanGelbart, Journal of the Society for Information Display, Vol. 11 Number1, pp. 199-202. The assemblage of thermal imaging donor and glass panelwas then exposed in a desired pattern from the back side first throughthe donor base film using a SQUARESPOT thermal imaging head manufacturedby Creo/Kodak. Vancouver, Canada. The rapidly moving head was equippedwith 830 nm infrared lasers with output energy of 21.5 watts was focusedto a spot size of about 5 μm×5 μm on the donor base film, or theinterface of the base film and a LTHC layer when a LTHC layer waspresent. Scan speeds typically ranged from 0.5 m/sec to 1.3 m/sec. Laseroutput was under computer control to build up the desired pattern. Laserpower and scan speed were controllable and were adjusted in an iterativefashion to optimize transfer quality as judged by visual inspection ofthe patterned catalyst layer on the receiver. The flatbed imager wasoperated in a controlled temperature/humidity environment with anaverage temperature of about 70° F. and an average relative humidity ofabout 45-55%.

Characterization Methods

Resistivity—Resistivity was measured using the four probe resistancefunction of a HP 3478A multimeter (Hewlett-Packard). Typically a squareof mesh ˜15 mm on a side was measured.

Thickness—Thickness of the transferred catalyst layer, Cu plating andblackening was determined using a KLA Tencor P-15 profiler.

Adhesion—A qualitative assessment of adhesion was made by using thefollowing criteria to assess whether a change in adhesion had occurred.When a small pointed probe was used to push on the metal lines of thepattern, a rating of 1-5 was given when the following was observed:

1 The metal line either did not come off substrate or only a small chipcame off and required significant force.

2 The metal line came off substrate in small pieces with significantforce applied.

3 The metal line came off substrate with minimal effort and adjoiningpieces loosened along edges.

4 The metal line lifted off substrate with little effort and pulled offsmall sections of adjoining mesh.

5 The metal line came off substrate independent of contact or whencontacted pulls off substrate as single piece.

TABLE 1 Glossary of Materials Descriptor Generic name/structure SourceAmertech polyester binder, 30% American Inks and Polyester Clear ®aqueous solution Coatings Corp; Valley Forge; PA BYK ®-025 Siliconedefoamer BYK-Chemie USA, Inc., Wallingford, CT CARBOSET GAStyrenic-acrylic polymer Noveon, Cleveland, 2300 Ohio Cymel ™ 350Melamine formaldehyde Cytec Industries Inc. resin West Paterson, NJDuPont P2449 RuO₂ DuPont Electronics- Microcircuit Materials, ResearchTriangle Park, NC DEGDB di(ethylenegylcol)di- Aldrich Chemical Co.,benzoate Milwaukee, WI EG2922SMZ, Glass frit, d50 = Ferro Corporation,0.83 micron Cleveland, OH EBONOL ®-C Sodium chlorite/sodium CooksonElectronics. hydroxide solution Providence, RI ELVACITE ® 2028 acrylicpolymer Lucite International, Glass-B = R3838 Glass frit, DuPontElectronics- d50 = 0.48 micron, Microcircuit Materials, d90 = 0.83micron Research Triangle Park, NC JONCRYL ® 538 acrylic polymer emulsionJohnson Polymer, Racine, WI MELINEX ® polyester film DuPont Teijin Film,ST504 Hopewell, VA PRIMID ® XL552, Ethoxylated diamide EMS Chemie, (VII)Domat/Ems, Switzerland SDA 4927 near-IR dye H.W. Sands Co., Jupiter, FLTegoWet ™ 251(4) Polyether modified Degussa, Hopewell, Va polysiloxanecopolymer ZONYL FSA Anionic fluoro surfactant E.I. DuPont de Nemours,Inc., Wilmington, DEOrganic LTHC Layer. The organic LTHC layer was prepared as reported inFormulation L of the Examples of PCT/US05/38009, referenced above:

A LTHC coating formulation was prepared from the following materials:(i) demineralised water: 894 g; (ii) dimethylaminoethanol: 5 g; (iii)Hampford dye 822 (Hampford Research; formula corresponds to SDA 4927):10 g; (iv) polyester binder (Amertech Polyester Clear; American Inks andCoatings Corp; Valley Forge; Pa.): 65 g of a 30% aqueous solution; (v)TegoWet™ 251 (4) polysiloxane copolymer: 2.5 g; (vi) potassiumdimethylaminoethanol ethyl phosphate: 14 g of an 11.5% aqueous solution[The 11.5% aqueous solution was prepared by combining three parts waterand 0.5 parts ethyl acid phosphate (Stauffer Chemical Company, Westport,Conn.: Lubrizol, Wickliffe, Ohio) and sufficient 45% aqueous potassiumhydroxide to achieve a pH of 4.5, followed by addition of sufficientdimethylaminoethanol to achieve a pH of 7.5 and finally dilution withwater to achieve five parts total of final aqueous solution of 11.5relative mass percent of water-free compound.]; (vii) crosslinker Cymel™350 melamine formaldehyde resin, Cytec Industries Inc. West Paterson,N.J.: 10 g of a 20% solution; and (viii) ammonium p-toluene sulphonicacid: 2 g of a 10% aqueous solution.

Ingredients (ii) and (iii) were added to the water and allowed to stirfor up to 24 hours before addition of the other ingredients in the ordershown. There was no need to filter this formulation. The formulation wasapplied in an in-line coating technique as follows: A PET base filmcomposition was melt-extruded, cast onto a cooled rotating drum andstretched in the direction of extrusion to approximately 3 times itsoriginal dimensions at a temperature of 75° C. The cooled stretched filmwas then coated on one side with the LTHC coating composition to give awet coating thickness of approximately 20 to 30 μm. A direct gravurecoating system was used to apply the coatings to the film web. A 60QCHgravure roll (supplied by Pamarco) rotates through the solution, takingsolution onto the gravure roll surface. The gravure roll rotates in theopposite direction to the film web and applies the coating to the web atone point of contact. The coated film was passed into a stenter oven ata temperature of 100-110° C. where the film was dried and stretched inthe sideways direction to approximately 3 times its original dimensions.The biaxially stretched coated film was heat-set at a temperature ofabout 190° C. by conventional means. The coated polyester film is thenwound onto a roll. The total thickness of the final film was 50 μm; thedry thickness of the transfer-assist coating layer is of 0.07 μm. ThePET base film contained Solvent Green 28 dye to give a final dyeconcentration of typically 0.2% to 0.5% by weight in the polymer of thebase film. The base film containing the Solvent Green 28 dye (0.40% byweight) had an absorbance of 1.2 at 670 nm, and an absorbance of <0.08at 830 nm. The donor substrate will herein be referred to as: OrganicLTHC Green PET donor substrate.

Example 1

This example illustrates the formation of a blackened copper plated meshusing a glass frit as an adhesion promoter.

A thermal transfer donor comprising a base film and a catalyst layer wasfirst prepared using the following procedure. A mixture of Ag powder(26.244 g, particle size d50=220 nm and d90=430 nm), Di water (10.358g), CARBOSET GA 2300 styrenic-acrylic polymer (13.404 g, 28 wt % inwater) ZONYL FSA surfactant (0.523 g, BYK-025 defoamer (0.299 g) andglass frit (0.529 g, EG2922SMZ, Ferro Corporation, Cleveland, Ohio) wastreated with a sonication probe (Dukane Co. Model 40TP200, TransducerModel 41C28) for 15 min, during which time the mixture was stirred witha spatula at 5 min intervals. The container with the mixture was placedin a water bath with sonication for 1 h, during which time the mixturewas stirred with a spatula at 0.5-h intervals. The mixture was thentreated in a water bath at RT with probe sonication for additional 15min, during which time the mixture was stirred gently with a spatula at5-minute intervals. The resulting dispersion was filtered twice with 2.0micron WHATMAN GFM-150 syringe-disc filter (Whatman Inc., Clifton,N.J.).

An organic LTHC Green PET thermal transfer donor base film was cleanedwith a pressurized nitrogen stream immediately prior to coating. Theabove dispersion was drawn on to the base film using a CN# 5 rod(Buschman Corporation, Cleveland, Ohio) at 5.8 ft/min utilizing aWATERPROOF Color Versatility coating system (E.I. DuPont De Nemours,Inc., Wilmington, Del.). The wet films were dried for 20 min at 48° C.to provide a thermal transfer donor comprising a base film and a silvercatalyst layer.

The thermal transfer donor was placed in vacuum contact with a glasspanel (boro-aluminosilicate glass ˜0.7 mm thick). This glass receiverwas mounted on a flatbed scanner as described above. Thermal transferwas preformed by exposing the donor to imaging radiation from theimaging head with total laser power at the image plane of about 20.5 Wusing scan speeds from varying from 0.5 to 1.3 m/sec in straight-linepatterns of about 5 mm.

After transferring the patterned catalyst layer, the spent donor wasremoved from the glass, providing the patterned substrate. The patternedglass substrate was then heated at an anneal temperature in a FisherScientific ISOTEMP Programmable Muffle Furnace Model 650 heated to 525°C. at a rate of 10° C./min and left at that temperature for 15 mm. Thesample was then cooled to near room temperature (RT) by turning off thepower to the furnace. After annealing the sample mesh had a resistivityof 110 Ω/square and was difficult to remove by scraping with probe.

The patterned substrate was then prepared for electroplating by applying½″ wide Cu tape, having a conductive adhesive, along the periphery ofthe silver pattern. Electroplating was preformed in a Technic, Inc.“Mini Plating Plant 3” electroplating system. The copper plating bathelectrolyte was “PC-65” with the brightner “PC 65 B” added at 1% byvolume. Both are manufactured by Technic Inc., Cranston R.I. The platingbath was kept at 22° C. during plating. A current density of 118 Amp/m²was applied to the patterned substrate for 400 sec depositing about 8 μmof copper on the silver pattern to provide a patterned copper layerhaving a resistivity <0.2 Ω/square. FIG. 6 is a photomicrograph of thepatterned metal layer.

Blackening of the patterned Cu layer was performed by immersing theplated patterned substrate in a 50 wt % solution of EBONOL-C (vendor,city state) heated to 100° C. for 120 sec. The resulting blackenedcopper plated mesh had a resistivity of <0.2 Ω/square and lowreflectance.

Example 2

This example illustrates the formation of a blackened Cu plated meshusing TYZOR® 212 organo zirconate added as an adhesion promoter.

A donor sheet was prepared using the same general procedure as outlinedin Example 1 and the ingredients and process variables listed in Table 2and 3. The donor sheet was imaged onto a glass plate in the flat bedimager previously described. The imaging speed was 0.5 m/sec. Afterimaging, the donor sheet was removed from the glass, providing apatterned substrate having an imaged Ag pattern. The patterned substratewas heat-treated in a Fisher Scientific Isotemp Programmable MuffleFurnace Model 650 to 230° C. at a rate of 10° C./min and left at thattemperature for 15 min. The patterned substrate was then cooled to RT byturning off the power to the heating elements.

Electroplating of the heat-treated patterned substrate was done in thesame manner as described in Example 1 except a current density of ˜248Amp/m² was applied to the sample for 300 sec, to provide a patterned Culayer with a Cu thickness of about 5.7 μm. The resistivity of the Cuplated mesh was <0.2 Ω/square.

Blackening of the patterned Cu layer was done by immersing the platedpatterned substrate in a 100% solution of Ebonol-C heated to 100° C. for7 seconds. The resulting mesh had good conductivity and low reflectance.

TABLE 2 Catalyst Compositions for Examples 2-5 Example No. Material 2 34 5 Ag powder, g 26.246 26.255 22.551 22.510 Water, g 10.370 10.368 — —Xylenes, g — — 14.999 15.012 CARBOSET 12.393 13.422 GA 2300, g ELVACITE— — 12.518 12.506 2028 ZONYL FSA 0.530 0.524 — — BYK-025 0.308 0.302 — —DEGDB 0.053 0.053 TYZOR 212 1.160 — — — PRIMID — 0.608 — — XL552 Glass-B0.448Ag powder particle size d50=220 nm and d90=430 nm; Ag flake F=equivalentspherical diameter of flake, d50/d90=870/1780; Glass-B=R3838.

TABLE 3 Catalyst Blending and Coating Parameters for Examples 2-5Example No. Parameter 2 3 4 5 1^(st) Sonication 15 15 15 15 probe time,min Stir frequency, 5 5 5 5 min Ultraconic bath 60 60 60 60 time, minStir frequency, 30 30 30 30 min 2^(nd) Sonication 15 15 15 15 probetime, min Stir frequency, 5 5 5 5 min Filter size, micon 2 2 2 2 Numberof 2 2 2 2 filterings Coating rod CN5 CN5 CN4 CN7 Coating speed, 1.771.77 1.77 1.77 m/min Dry time, min 20 20 20 20 Drying temp, ° C. 48 4845 46

Example 3

This example illustrates the formation of a blackened Cu plated meshusing an organic polyol, PRIMID® XL552 polyol, added as an adhesionpromoter.

A donor sheet was prepared using the same general procedure as outlinedin Example 1 and the ingredients and process variables listed in Table 2and 3. The donor sheet was imaged onto a glass plate in the flat bedimager previously described. The imaging speed was 0.5 m/sec.

After imaging, the donor sheet was removed from the glass, providing apatterned substrate having an imaged Ag pattern. The patterned substratewas heat-treated in a Fisher Scientific Isotemp Programmable MuffleFurnace Model 650 to 230° C. at a rate of 10 C/mm and left at thattemperature for 15 mm. The patterned substrate was then cooled to RT byturning off the power to the heating elements. The resistivity of theheat treated Ag mesh was 144 Ω/square.

Electroplating of the heat-treated patterned substrate was done in thesame manner as described in Example 1 except a current density of about248 Amp/m² was applied to the sample for 300 sec, to provide a patternedCu layer with a Cu thickness of ˜5.7 μm. The resistivity of the Cuplated mesh was <0.2 Ω/square.

Blackening of the patterned Cu layer was done by immersing the platedpatterned substrate in a 100% solution of Ebonol-C heated to 100° C. for7 seconds. The resulting mesh had a resistivity of <0.2 Ω/square and lowreflectance.

Example 4

This example illustrates the formation of a Cu plated mesh in theabsence of an adhesion promoter.

A donor sheet was prepared using the same general procedure as outlinedin Example 1 and the ingredients and process variables listed in Table 2and 3. The donor sheet was imaged onto a glass plate in the flat bedimager previously described. The imaging speed was 0.9 m/sec.

Electroplating of the patterned substrate was done in the same manner asdescribed in Example 1 except a current density of ˜124 Amp/m² wasapplied to the sample for 480 sec depositing ˜7 μm of Cu. The resultingmesh had a resistivity of <0.2 Ω/square.

Example 5

This example illustrates the creation of a blackened Cu plated mesh.

A donor sheet was prepared using the same general procedure as outlinedin Example 1 and the ingredients and process variables listed in Table 4and 5. The donor sheet was imaged onto a glass plate in the flat bedimager previously described. The imaging speed was 0.6 m/sec.

After imaging, the donor sheet was removed from the glass, providing apatterned substrate having an imaged Ag pattern. The patterned substratewas heat-treated in a furnace to 525° C. at a rate of 10 C/min and leftat that temperature for 15 min. The patterned substrate was then cooledto RT by turning off the power to the heating elements. The heattreatment provided an Ag pattern with good adhesion to the substrate.

Electroplating was performed in the same manner as described in Example1 except a current density of ˜124 Amp/m² was applied to the sample for200 sec depositing ˜1.4 μm of Cu on the patterned catalyst layer. Theplated pattern showed slight delamination at edge of pattern.

Blackening of the plated Cu pattern was performed by immersing thepatterned metal layer in a 50% solution of Ebonol-C heated to 100° C.for 60 sec. The resulting mesh had good conductivity and lowreflectance. The blackened sample had poor adhesion to the glass and waseasily removed from the glass plate.

Example 6

This example illustrates the creation of a Cu plated mesh using a glassfrit as an adhesion promoter.

A donor sheet was prepared using the same general procedure as outlinedin Example 1 and the ingredients and process variables listed in Table 4and 5. The donor sheet was imaged onto a sheet of MELINEX® ST504 usingthe CREO TRENDSETTER® 800 previously described. Imaging was done with adrum rotation speed of 60 rpm and laser powers of 6.9, 7.0, 7.1 and 7.2W.

Electroplating of the patterned substrate was done in the same manner asdescribed in Example 1 except a current density of ˜226 Amp/m² wasapplied to the sample for 480 sec depositing about 7 μm of Cu. Theresulting mesh had a resistivity <0.2

/square.

TABLE 4 Catalyst Compositions for Examples 6-9 Example No. Material 6 78 9 Ag powder, g — 26.261 — — Ag flake, g 27.108 — 26.247 32.397 Water,g 16.346 15.410 10.372 19.605 CARBOSET — — 13.411 GA 2300, g JONCRYL6.697 8.342 — 8.007 538 ZONYL FSA 0.546 0.525 0.523 0.648 BYK-025 0.3100.501 0.309 0.466 TYZOR 212 — — 1.160 —Ag powder particle size d50=220 nm and d90=430 nm; Ag flake F=equivalentspherical diameter of flake, d50/d90=870/1780; Glass-B=R3838.

TABLE 5 Catalyst Blending and Coating Parameters for Examples 6-9Example No. Parameter 6 7 8 9 1^(st) Sonication 15 15 15 probe time, minStir frequency, 5 5 5 min Ultraconic bath 60 60 60 time, min Stirfrequency, 30 30 30 min 2^(nd) Sonication 15 15 15 probe time, min Stirfrequency, 5 5 5 min Filter size, micon 12, 8 2 12, 8 12, 8 Number of 1each 2 1 each 1 each filterings Coating rod CN4 CN5 CN5 CN4 Coatingspeed, 1.77 1.77 1.77 1.77 m/min Dry time, min 20 20 20 20 Drying temp,° C. 44 46 46 46

Example 7

This example illustrates the formation of a Cu plated mesh.

A donor sheet was prepared using the same general procedure as outlinedin Example 1 and the ingredients and process variables listed in Table 4and 5. The donor sheet was imaged onto a glass plate in the flat bedimager previously described. The imaging speed was 0.9 m/sec.

Electroplating was performed using the same technique as described inExample 1. The patterned metal layer delaminated from the substrateunder all plating conditions.

Example 8

This example illustrates the creation of a Cu plated mesh on a glassplate.

A donor sheet was prepared using the same general procedure as outlinedin Example 1 and the ingredients and process variables listed in Table 4and 5. The donor sheet was imaged onto a glass plate in the flat bedimager previously described. The imaging speed was 0.8 m/sec.

Electroplating was done in the same manner as described in Example 1except a current density of ˜248 Amp/m² was applied to the sample for200 sec depositing 1.5 μm of Cu. Deposition of Cu was irregularsuggesting that portions of the original image were isolated from theplating electrodes by breaks in the pattern or by other non-conductiveelements in the pattern. The resulting plated areas of the mesh had aresistivity of about 0.5 Ω/square/.

Example 9

This example illustrates the creation of a Cu plated mesh on a triacetylcellulose film.

A donor sheet was prepared using the same general procedure as outlinedin Example 1 and the ingredients and process variables listed in Table 4and 5. The donor sheet was imaged onto a sheet of TAC film using theCREO TRENDSETTER® 800 previously described. Imaging was done with a drumrotation speed of 40 rpm and laser power of 4.0 W.

Electroplating was done in the same manner as described in Example 1except a current density of ˜344 Amp/m² was applied to the sample for180 sec depositing ˜5 μm of Cu. The resulting mesh had a resistivity<0.2 Ω/square.

Example 10

This example illustrates the formation of a blackened Cu plated meshusing a glass frit as an adhesion promoter.

A donor sheet was prepared using the same general procedure as outlinedin Example 1 and the ingredients and process variables listed in Table 6and 7. The donor sheet was imaged onto a glass plate in the flat bedimager previously described. The imaging speed was 0.6 m/sec.

After imaging, the donor sheet was removed from the glass, providing apatterned substrate having an imaged Ag pattern. The patterned substratewas then heat-treated in a furnace heated to 525 C at a rate of 10 C/minand left at that temperature for 15 min. The sample was then cooled tonear RT by turning off the power to the heating elements. The heattreatment provided a Ag pattern with good adhesion to the substrate.

Electroplating was done in the same manner as described in Example 1except a current density of 516 Amp/m² was applied to the sample for 111sec. The resulting plated mesh had a resistivity <0.2 Ω/square and hadgood adhesion to the substrate.

Blackening of the plated Cu was performed by immersing the plated samplein a 50% solution of Ebonol-C heated to 100° C. for 60 sec. Theresulting mesh had a resistivity <0.2 Ωsquare and low reflectance. Theblackened sample had good adhesion to the glass substrate.

TABLE 6 Catalyst Compositions for Examples 10-12 Example No. Material(g) 10 11 12 Ag powder, 22.527 19.246 22.501 Xylenes, 15.005 15.00715.001 ELVACITE ® 12.530 12.519 12.508 2028 DEGDB 0.056 0.049 0.048EG2922SMZ 0.448 0.591 DuPont — — 0.452 R3838 RuO₂ — 2.665 — DuPont P2449

TABLE 7 Catalyst Blending and Coating Parameters for Examples 10-12Example No. Parameter 10 11 12 1^(st) Sonication 15 15 15 probe time,min Stir frequency, 5 5 5 min Ultraconic bath 60 60 60 time, min Stirfrequency, 30 30 30 min 2^(nd) Sonication 15 15 15 probe time, min Stirfrequency, 5 5 5 min Filter size, micon 2 2 45 Number of 2 2 1filterings Coating rod CN4 CN5 CN7 Coating speed, 5.8 5.8 5.8 m/min Drytime, min 20 20 20 Drying temp, ° C. 47 46 47

Example 11

This example illustrates the creation of a blackened Cu plated meshusing a glass frit as adhesion promoter, and RuO₂ as a blackening agentfor the patterned catalyst layer.

A donor sheet was prepared using the same general procedure as outlinedin Example 1 and the ingredients and process variables listed in Table 6and 7. The donor sheet was imaged onto a glass plate in the flat bedimager previously described. The imaging speed was 0.6 m/sec.

After imaging, the donor sheet was removed from the glass, providing apatterned substrate having an imaged Ag pattern. The patterned substratewas then heat treated in a furnace heated to 525 C at a rate of 10 C/minand left at that temperature for 15 min. The sample was then cooled tonear RT by turning off the power to the heating elements. The heattreatment provided a Ag pattern with good adhesion to the substrate.

Electroplating was done in the same manner as described in Example 1except a current density of ˜516 Amp/m² was applied to the sample for111 sec. The resulting mesh had a resistivity ˜0.5 Ω/square. Theresulting plated pattern exhibited good adhesion to the substrate.

Example 12

This example illustrates the formation of a patterned metal layer on apatterned substrate having a patterned black layer thereon.

A first donor sheet comprising Cr₃O₄ was prepared following the samegeneral procedure as outlined in Example 1 with the followingingredients: xylenes (12.018 g), ELVACITE®2028 (21.264 g) DEGDB (0.082g), glass frit (EG 2922 SMZ, 8.612 g) and DuPont 1-2218 Cr₃O₄ powder(12.161 g). A second donor sheet containing a catalyst layer wasprepared using the same general procedure as described in Example 1 andthe ingredients and process variables listed in Table 6 and 7.

The first donor sheet was imaged onto a glass plate in the flat bedimager previously described. The imaging speed was 0.7 m/sec. The firstimaged donor sheet was removed to provide a patterned substrate having apatterned black layer thereon. Without changing the position of thepatterned substrate the second donor sheet was imaged onto the patternedsubstrate within the limits of the patterned black layer using animaging speed of 0.7 m/sec.

After imaging, the second imaged donor sheet was removed to providepatterned substrate having, in layered sequence, a Ag catalyst layer, ablack layer, and the glass substrate. The patterned substrate was thenheat-treated in a furnace heated to 525° C. at a rate of 10° C./min andleft at that temperature for 15 min. The sample was then cooled to nearRT by turning off the power to the heating elements. The heat treatmentprovided a Ag pattern with good adhesion to the substrate.

Electroplating was done in the same manner as described in Example 1except a current density of ˜190 Amp/m² was applied to the sample for 40sec depositing about 4 microns of Cu. The resulting plated patternshowed good conductivity. FIG. 7 shows a photomicrograph of the platedpattern within the bounds of the patterned black layer.

TABLE 6 Catalyst Compositions for Examples 10-12 Example No. Material(g) 10 11 12 Ag powder, 22.527 19.246 22.615 Xylenes, 15.005 15.00715.000 ELVACITE ® 12.530 12.519 12.502 2028 DEGDB 0.056 0.049 0.052EG2922SMZ 0.448 0.591 EG2888SMZ — — 0.901 RuO₂ — 2.665 — DuPont P2449

TABLE 7 Catalyst Blending and Coating Parameters for Examples 10-12Example No. Parameter 10 11 12 1^(st) Sonication 15 15 15 probe time,min Stir frequency, 5 5 5 min Ultraconic bath 60 60 60 time, min Stirfrequency, 30 30 30 min 2^(nd) Sonication 15 15 15 probe time, min Stirfrequency, 5 5 5 min Filter size, micon 2 2 2 Number of 2 2 2 filteringsCoating rod CN4 CN5 CN4 Coating speed, 5.8 5.8 5.8 m/min Dry time, min20 20 20 Drying temp, ° C. 47 46 47

1. A method for making a patterned metal layer having high conductivitycomprising: providing a patterned substrate comprising a patternedcatalyst layer on a base substrate; said patterned substrate made by athermal imaging method comprising: (a) providing a thermal transferdonor comprising a base film and a catalyst transfer layer, wherein thecatalyst transfer layer comprises: (i) a catalyst fraction; optionally(ii) an adhesion promoter fraction; and, optionally and independently,(iii) a polymer binder fraction; (b) contacting the thermal transferdonor with a receiver, wherein the receiver comprises a base layer; and(c) transferring at least a portion of the catalyst transfer layer ontothe receiver by thermal transfer to provide a patterned receiver as saidpatterned substrate; and plating metal onto said patterned substrate, toprovide the patterned metal layer in connectivity with the patternedcatalyst layer, wherein said plating metal onto said patterned substrateis done by electroplating.
 2. The method of claim 1 wherein the catalysttransfer layer and patterned catalyst layer have an adhesion promoterfraction selected from metal oxides; metal hydroxides and alkoxides;silicate hydroxides and alkoxides; and organic polyols.
 3. The method ofclaim 1 wherein the catalyst fraction comprises one or more catalyst(s)selected from the group: (1) metal particles; (2) metal oxides; (3)organic metal complexes; (4) organic metal salts; (5) ceramics and othernon-conductor powders coated with metal salts, metal oxides, metalcomplexes, metal or carbon; and (6) carbon in all conductive forms; eachmetal of (1) to (5) selected from the group consisting of: Ag, Cu, Au,Fe, Ni, Al, Pd, Pt, Ru, Rh, Os, Ir, Sn and alloys thereof.
 4. The methodof claim 1 wherein the catalyst transfer layer and patterned catalystlayer comprise about 1.0 to 99 wt % catalyst fraction; about 0.5 to 10wt % adhesion promoter fraction; and about 0.5 to 98.5 wt % polymerbinder fraction.
 5. The method of claim 1 wherein the transferring isachieved through a laser mediated transfer and said laser has anoperating wavelength of about 350 to 1500 nm.
 6. The method of claim 1wherein the thermal transfer donor further comprises an LTHC layer,disposed between the base film and the catalyst transfer layercomprising one or more radiation absorbers selected from the groupconsisting of: metal films selected from Cr and Ni; carbon black;graphite; and near infrared dyes with an absorption maxima in the rangeof about 600 to 1200 nm within the LTHC layer.
 7. The method of claim 1wherein the thermal imaging method further comprises: (d) heating thepatterned substrate to an anneal temperature for an anneal period toprovide the annealed patterned substrate; and said plating metal,comprises plating said annealed patterned substrate.
 8. The method ofclaim 1 wherein said thermal transfer donor further comprises, on thecatalyst transfer layer opposite the base film, an adhesion promoterlayer; and said transferring further comprises transferring acorresponding proximate portion of the adhesion promoter layer toprovide said patterned substrate having, in layered sequence on saidreceiver, a patterned adhesion promoter layer and said patternedcatalyst layer.
 9. A thermal transfer donor comprising a base film, acatalyst transfer layer (A), and a LTHC layer interposed between saidbase film and said catalyst transfer layer (A), said catalyst transferlayer (A) comprising: (i) about 1.0 to about 99 wt % of a catalystfraction (A), based on the total weight of the catalyst layer, saidcatalyst fraction comprising metal particles selected from Ag, Cu, andalloys thereof; (i) about 0.5 to about 10 wt % of an adhesion promoterfraction selected from metal hydroxides and alkoxides; (ii) about 0.5 toabout 98.5 wt % of a polymer binder.
 10. The donor of claim 9 whereinthe LTHC layer comprises one or more radiation absorbers selected fromthe group consisting of: metal films selected from Cr and Ni; carbonblack; graphite; and near infrared dyes with an absorption maxima in therange of about 600 to 1200 nm within the LTHC layer.
 11. A thermaltransfer donor comprising, in layered sequence, a base film, a catalysttransfer layer (B) and an adhesion promoter layer, said catalysttransfer layer (B) comprising: (i) about 1.0 to about 99 wt % of acatalyst fraction, based on the total weight of the catalyst layer, saidcatalyst fraction comprising metal particles selected from Ag, Cu, andalloys thereof; (iii) about 1.0 to about 99 wt % of a polymer binder;and wherein the adhesion promoter layer comprises material selected frommetal hydroxides and alkoxides.
 12. An electronic device having apatterned metal layer on a substrate, said substrate substantiallytransparent to visible light; said patterned metal layer comprising, inlayered sequence on said substrate: an adhesion promoter layer, acatalyst layer, and a plated metal layer; and said patterned metal layerhaving at least one line of width of about 1 millimeter or less, whereinthe adhesion promoter layer comprises material selected from metalhydroxides and alkoxides; and the catalyst layer comprises (i) about 1.0to about 99 wt % of a catalyst fraction, based on the total weight ofthe catalyst layer, said catalyst fraction comprising metal particlesselected from Ag, Cu, and alloys thereof; and (ii) about 1.0 to about 99wt % of a polymer binder.
 13. The electronic device of claim 12, whereinthe adhesion promoter layer further comprises an antireflective agentfraction; and the patterned metal layer further comprises anantireflective layer on the metal layer opposite the adhesion promoterlayer.
 14. The electronic device of claim 12 that is an electromagneticinterference (EMI) shield or a touchpad sensor.